The following is a very tiny excerpt from my new book (tentatively titled “Forging the Ultimate Physique”). It deals with the much misunderstood concept of intramuscular tension and why it is so critical for success in strength training and bodybuilding. In a nutshell, if you wish to get bigger and/or stronger you must do everything you can to increase the intramuscular tension of the muscles being trained – adopt the mantra “lift heavier, fight gravity” (both ways..read on and you’ll follow my meaning).
“The goal of everyone reading this book should be to get bigger and/or stronger (the two don’t always have to go hand in hand) and supposing that to be the case then the one training principle that I want to drum into your head above anything else is the importance of creating high levels of intramuscular tension. Forget all the fancy theories of burns, partial reps, forced reps and stilted reps (OK, I made that last one up), the one most significant training stimulus for creating an adaptive response of strength and size development is intramuscular tension.
Intramuscular tension is a measure of the force (in this case load/resistance multiplied by acceleration) a given muscle is required to produce. So, in other words any increase in weight and/or acceleration will increase intramuscular tension, which in turn will cause an increase in the worked muscle’s rate of protein degradation and subsequent post workout amino acid uptake. All of which equates to larger, stronger muscles. In practical terms this means that every trainee should strive to lift heavier weights (there appears to be a minimum load threshold for achieving high intramuscular tension – for these purposes definitely use a weight that is no lighter than your 12RM otherwise you will not be able to tap into the high threshold muscle fibres necessary for creating concurrently high levels of intramuscular tension) in a manner that will cause the highest degree of intramuscular tension.
So for the concentric/positive portion of movement the aim is to accelerate the weight (do I need to add that the weight should always be under control) as quickly as possible*. For the eccentric/negative part of the movement the opposite holds true as lowering faster requires less force and therefore generates less tension. A controlled (3-5 second) negative is therefore an essential part of creating the necessary high level of intramuscular tension.
In his excellent book “The Black Book of Training Secrets”, Christian Thibadeau uses the example of the physiques of Olympic lifters of yesteryear whose more muscular bodies than their present day counterparts could be credited to the fact that they had to lower their barbells under control (emphasising the negative) as they didn’t have bumper plates. Anyway, in which a trainee can increase intramuscular tension is to be encouraged, so long as it is not overtaxing to his recovery ability. More advanced trainee’s for example (with a training age over 2 years) can benefit from using chains or bands that positively adapt the strength curve to increase the amount of tension throughout the strength curve of the given movement (such as the increased load on a bench press with chains as you move up the strength curve).
* If you concentrate on accelerating the load with a weight that will target your high threshold motor units (1-5 repetition maximum), actual speed is irrelevant for creating intramuscular tension so long as your brain and nervous system intend to move the bar as quickly as possible in the concentric phase. The same does not hold true of accelerating with higher reps as they would still only access lower threshold muscle fibres”.